Pump stations are generally exposed to various problems which affect efficiency, performance, reliability, operating life of the pumps, and maintenance cost. Vibration in pumps may be a result of improper installation, lack of maintenance, weak foundation, resonance and etc. Axial flow pumping system is usually used to deliver high discharges at low heads. Vertical and inclined installations of these pumping systems cause structural vibration problems for such plants. Axial Flow Pumping stations always have long rotating shafts working as a cantilever fixed at the bottom (pump) and free at the top (motor). The objective of this research is to identify the causes of the high vibration of El-Marashda (1) pumping station due to weakness of the foundation. Effect of adding steel to supports motor foundation is studied to overcome structural weakness of the vertical pump support. Vibration level was measured and frequency analysis was also done on the pumps parts and on the foundations by adding steel supports gradually at different conditions to determine the source of vibration and the path of vibration transmission to the foundation. From initial measurements, vibration levels measured on all units are in the danger level. Different case studies are evaluated at different conditions experimentally to obtain the optimum dynamic conditions. Adding steel supports to motor foundation at two stages gradually fixed the problem and reduced the high vibration level. Firstly, adding steel supports to motor foundation reduced the velocity vibration level 53%, reduced the acceleration vibration level 24%, and reduced the bearing defect factor (BDF) 22%. Finally, increasing steel supports to motor foundation reduced the velocity vibration level 91%, reduced the acceleration vibration level 91%, and reduced the BDF 56%. The dynamic characteristics of the pump structure have improved and the measured vibration level is safe. Vertical pump foundation should be carefully designed and strengthened to resist the dynamic loads. Inspection and regular maintenance is important to avoid any abnormal conditions leading to dynamic loads affecting both pump components and foundation.
Keywords: Dynamic Performance, Pump Vibration
